TanDEM-X: A Spaceborne Bistatic Radar Interferometer

After the successful participation in the Shuttle missions SIR-C/X-SAR and SRTM, the first national SAR mission TerraSAR-X opened a new era in the German Space Programme and provided a major push for our R&D activities on high resolution X-band SAR based on active phased array T/R module technology. The TerraSAR-X mission spacecraft TSX has been successful launched from Baikonur on June 15, 2007 and since day 5 of mission the TerraSAR-X ground segment is providing superior high resolution SAR images for purposes of scientific observation of the Earth for a period of at least five years after the commissioning phase. At the same time it is designed to satisfy the steadily growing demand of the private sector for remote sensing data in the commercial market. In this spirit, the proposal to add a second, almost identical spacecraft, TDX, to the TSX spacecraft and to fly the two satellites in a closely controlled tandem formation building a single-pass SARinterferometer with adjustable baselines in across- and in alongtrack directions was born. With typical across-track baselines of 250-500 m Digital Elevation Models (DEMs) according to the High Resolution Terrain Information (HRTI)-3 standard will be generated. This synchronized, mainly bistatic operation of TSX and TDX is called the TanDEM-X mission. Like TerraSAR-X the TanDEM-X mission is being implemented in a public-private partnership between the German Aerospace Centre (DLR) and the EADS Astrium GmbH. The launch of the TDX spacecraft is planned for 2009.